This invention relates to methods and compositions for inhibiting the corrosion of metal components which are contacted by aqueous fluids.
More particularly, this invention relates to the use of filming amine emulsions containing ethoxylated beta amines and diamines in order to inhibit the corrosion of metal components in aqueous systems. The term "metal components" is intended to include ferrous materials and alloys, non-ferrous alloys, such as, copper or nickel-based alloys, and the "aqueous systems" is intended to include steam boiler systems, steam return condensate systems, steam distribution systems, heat transfer water systems, evaporator systems, processing water systems, and various heating and cooling water systems.
Previous attempts to inhibit corrosion experienced under the described conditions have also employed aliphatic amines. In such treatments, as in the present invention, it is theorized that the treating materials are entrained in the corrosive fluids and deposit to form a protective film upon the metal surfaces. For example, U.S. Pat. No. 2,460,259, issued to Kahler, disclosed the use of aliphatic amines of a relatively high molecular weight. While such amines yield satisfactory corrosion inhibition, they present a number of problems in respect to processing, function, economics and feeding. First, the fact that those amines which yield adequate corrosion inhibition are solids at room temperature, necessitates their transformation to a liquid state. Secondly, effective utilization requires a composition which may be accurately metered to and dispersed within the system to be treated. Since the extremely low water solubility of corrosion inhibiting aliphatic amines has resisted dispersion in such systems, it has been the practice to prepare dilute aqueous dispersions which are then metered and fed to the system to be treated. However, even the preparation of these dilute intermediate dispersions has entailed the utilization of these amines either in the form of salts as disclosed by U.S. Pat. No. 2,712,531, issued to Maguire, or in combination with dispersant aids or emulsifiers as disclosed by U.S. Pat. No. 3,088,796, issued to Kahler et al. In such cases, the salts and dispersant aids do not directly contribute to the corrosion potential of the system, and the dispersant aids may recycle to the boiler, induce foaming, or form an undesirable precipitate. Furthermore, the conversion of the amines to liquids, salts or emulsions add appreciably to the treatment cost.
Other representative patents which disclose various amine corrosion inhibitors include U.S. Pat. Nos. 3,239,470; 3,382,186; 3,398,196; 3,444,090 and 3,717,433.